<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		
		<!-- <script>
			alert("Hello world");
		</script> -->
		
		<!-- 外部引入 -->
		<!-- 注意script要成对出现 -->
		<script src="js/first.js"></script>
	</head>
	<body>
	</body>
</html>
